The so-called tabless napkins have become increasingly popular over the past several years. These napkins rather than having extended areas at either end for attachment by means of a belt have an adhesive pattern on the garment facing side thereof for direct attachment to the garment. Napkins may have this adhesive applied directly to a fluid impervious baffle or to a fluid permeable outer wrap which is overwrapped in the adhesive area. In any event, however, adhesives utilized for attachment to undergarments have been of the pressure sensitive variety and are traditionally covered with a release liner. This release liner is usually a silicone treated release paper and is maintained with low adhesive force on the pressure sensitive adhesive until the napkin is ready for use. The release liner is peeled away and the napkin is then pressed into place activating the pressure sensitive adhesive by the force utilized in producing the contact with the undergarment.
There have been problems associated with the utilization of release liners, however. For example, a separate manufacturing step is necessary to attach the release liners. Furthermore, the properties of the adhesive must be matched to that of the release surface to provide sufficient adhesion for release liner attachment without providing a strong adhesive bond requiring substantial force to separate the release liner. Improper coating of the release liner can bring about a direct paper to adhesive bond which produces nonadhesive areas on the adhesive strip when release is attempted and, in extreme cases, can render the napkin unusable due to the defect in the attachment system.
In the past, there have been attempts to eliminate the release liner from sanitary napkins. These attempts have, however, met with indifferent success. German Pat. No. 2,644,032 teaches a self-adhesive napkin in which the adhesive is insulated from contact by a perforated polyurethane foam. When the napkin is attached the foam is compressed, making small selected areas of adhesive available.
U.S. Pat. No. 4,067,337 discloses a diaper tape which needs no protective release sheet because of the utilization of an open plastic netting which prevents direct contact with the pressure sensitive adhesive. While the problems inherent in this attachment means are substantially different than those utilized with a sanitary napkin, the broad approach to the solution is somewhat similar to that taught in the German Patent referred to above. U.S. Pat. Nos. 4,010,753 and 3,853,129 show structures similar to those disclosed in U.S. Pat. No. 4,067,377.
It is apparent that both the feminine napkin art and the art associated with diapers relies upon the introduction of a covering layer in which the adhesive is made available by expressing the adhesive surface through the covering. The subject invention provides an alternative approach for eliminating release liners while providing a sanitary napkin which can be rapidly made on essentially conventional equipment.